Traditionally, frequency spectrum access has been granted by regulatory authorities for exclusive use on permanent basis. This means that licensee has right for permanent reservation defined by regulatory authorities. Recently a new method known as Authorized Shared Access (ASA) or Licensed Shared Access (LSA) has been defined to complement existing spectrum licensing mechanisms.
Fast increase of smart phones penetration and subsequent growth of mobile broadband traffic means that there is huge need for finding new spectrum bands to serve the traffic. However, it is difficult to find new bands where there is wide enough bandwidth available and where the band has otherwise appealing characteristics. At the same time there are certain frequency bands that are reserved for e.g. military, costal guard or wireless camera type use but where the actual usage is typically limited to specific geographic location or times of the day or combinations of the two. In wide geographic areas and/or large parts of time the spectrum can be practically clean from signals. Hence it would be logical to create a formal reallocation framework which allows taking the low use spectrum into commercial use while maintaining incumbents' rights and ability to use the band when/where needed. ASA introduces this framework. However, the ASA framework is still under development and there are many open issues related to how the high level concept will be merged with technologies and solutions that are used in wireless broadband networks.
“Authorised Shared Access (ASA). An Innovative Model of Pro-competitive Spectrum Management,” by Nokia Corporation and Qualcomm Corporation is a white paper that is hereby incorporated herein by reference in its entirety. This white paper proposes dynamic sharing of spectrum resources. In other words, it proposes sharing, where allocations/assignments of available spectrum resources are static based on strict agreements and a dynamic component of sharing is provided when and where the shared spectrum is released by incumbent.
FIG. 1 illustrates an ASA spectrum sharing architecture according to a contemporary approach. As shown in FIG. 1, the architecture may include an ASA Repository 110, which is a database. This database contains the relevant information on spectrum use by the incumbent 120 in the spatial, frequency and time domains. For the purpose of ASA, an “incumbent” is defined as a current holder of spectrum rights of use. It is possible that the incumbent has been granted the spectrum rights through an award procedure (e.g. first-come, first-served, beauty contest, and auction). On the other hand, however, the incumbent 120 may be viewed as the original or default owner of the spectrum. For example, the incumbent 120 may be a government agency, such as the Department of Defense, the Department of Homeland Security, the Federal Aviation Administration or other spectrum users such as Satellite Services or Broadcasters. The database may add safety margins and deliberate distortions to the actual use data in order to mask the true activity of the incumbent 120. The incumbent 120 may not be willing to give precise information about its spectrum use to ASA licensees, for reasons primarily connected to the nature of its service, which may be defense operations, interference management, network security, emergency services or privacy. Due to the sensitive nature of the incumbent's information, in some cases the ASA repository 110 could be country-specific and under the purview of the National Regulatory Authority (NRA), such as the Federal Communications Commission or the National Telecommunications and Information Administration (NTIA). There could be one or more repositories per country, depending on the ASA band and the incumbent's nature: public or commercial. The ASA repository 110 may be directly managed by the administration or the NRA (illustrated in combination as the administrator/regulator 130) or by the incumbent 120, or be delegated to a trusted third party.
As shown in FIG. 1, the architecture may also include ASA controller 140. The ASA controller 140 computes ASA spectrum availability based on rules built upon ASA rights of use and information on the incumbent's use provided by the ASA repository 110. It connects to the ASA repository 110 through a secure and reliable interface. There could be one or multiple ASA controllers per country. The ASA controller 140 can interface with one or multiple ASA repositories as well as with one or multiple ASA networks. The ASA controller 140 may be managed by the administrator/regulator 130, the ASA licensee(s) 150 or a trusted third party.
ASA network operations, administration and maintenance (OAM) corresponds to the OAM of mobile broadband networks. The OAM in the ASA licensee network takes care of the actual management of the ASA licensed spectrum. In practical terms, the OAM translates into radio resource management (RRM) commands the information on spectrum availability obtained from the ASA controller 140. These commands are then transmitted to base stations 160, 165 in the ASA licensee's network, as contrasted to incumbent base station(s) 125. Based on this information, the base stations 160, 165 enable user devices 170 to access the ASA spectrum or order them to hand off seamlessly to other frequency bands as appropriate subject to, for example, ASA spectrum availability, quality of service (QoS) requirements, data rates or data plans. Information coming from the OAM also allows the base stations 160, 165 to tune to different channels or to power down.
One concern regarding the implementation of the ASA spectrum sharing architecture is how the ASA incumbents can give their licensed frequency spectrum to be used by ASA licensees without compromising the confidentiality of network configurations are conventionally classified information that are highly relevant to the business of the mobile network operators, i.e. the ASA licensee and the ASA incumbent.
Furthermore, the number of base stations that use the frequency spectrum, may have different characteristics, e.g. in terms of transmission power, directional patterns of antennas, antenna tilting angles and antenna gains to name a few. The differences may result e.g. from the sites using equipment from different manufacturers. Therefore, a frequency spectrum licensed to different ASA licensees using different equipment for transmissions may cause different results in terms of interference on the licensed frequency band.